Electromagnetic contactor



W. G. HARTWG ELECTROMAGNETIC CONTACTOR Filed Jan. 22, 1923 NNI @a NQ Patented Jan.v .3, 1928.'

UNITED STATES y 1,654,646 PATENT OFFICE.

WILLIAM G. HABTWIG, 01B: CHICAG, ELIANOIS, AASSIGNOR'TO E. J. MAGEBSTADT, 0I'

' 'CHIGAGCL ILLINOIS.

nnncrnomnenn'rc con'rnc'ron.

Application led January 22, 1923. Serial No. 614,069.

My invention is designed more particularly-er use in connection with heatingv er` cooling apparatus, though in some of its features, as will hereinafter appear, it is well adapted for a variety of prdposes inwhich current of some amperage is te be controlled. ln temperature control systems such as that chosen for exemplification of my invention,v heating or cooling means and a thermostat lo controlling the same are located in the inclosure, compartment or the like, the tem-v perature of which is te be regulated. Where a low temperature is te be maintained, a cooling means such as an, ice machine isconnected to heat absorbing'coils of pipe 1n said inclosure and the thermostat is used to oo nvtrol the operation of themotor, closing its circuit when the temperature rises above a predetermined point and opening its cir-l !0 cuit when the temperature falls below a predetermined point. Where a relatively high temperatureis te be maintained the temperature regulating means is commonly an Velectric heating coil, the circuit of which 1s controlled by athermostat which may be 'in circuit withan electromagnet directly er indirectly operating the movable contact member of the contacter. The 'thermestats commonly employed for such purposes are lo either of the bi-metallic movable arm type or of the thermometer type, both of which are .of somewhat delicate construction and not f vwell adapted for carrying large currents and this' is particularly true of the thermometer 3| tA i eef thermostat whichl have found more desirable for use in systems of thislrind in the respect that it is more sensitive and accurate'in operation Athan the other.- It is therefore important that the electromagnetic 4e means be such as may be operated-by a'V cemparatively small low voltage current.

the contacter carries a considerable current,-h'eatinggo1i power, unless-provision is 'madeto'the contrary, it rapidly is eaten 'a away b the dis-charge on breaking the'circuit an furthermore the movable contact is inclined .to 'stick to the stationary contact. In my improved contactor'the mechanical construction is such that when the heating 5o or .power circuit is opened the movable contact 'Y .ediately is widely separated from the stationary contact thus avoiding destructive arcing andthe movable contact closes 'against the stationary contact withv a rollingactionao that theline ofaclgual is jthe invention is also affords means for securingl slightly shifted after contact is rst'made, thus preventing sticking of the contacts together. Furthermore the connections for op-v erating the contacter preperl from the electromagnetic device are such t at a comparatively small lew voltage current is suiiicient to properly operate the movable element of the contacter` and hold it firmly against the stationary contact when the circuit through the contacter is closed.

Furthermore in my improved contacter provision is made for so insulatingthe low voltage electromagnetic device from the contaeter proper that all possible danger of the high voltage current getting into the low voltage circuit is obviated.

In the drawing accompanying and forming a\ part of this application I have described a preferred embodiment of the invention; it is to be understood, however, that the specific disclosure is for the purpose of exemplicatien only1 and that the scope of n l efined in the following claims in which I have endeavored to distinguish it from the prior arts so far as lmown to me without, however, relinquishing or abandoning any. portion or feature thereof.

In the drawing Figul is a side elevation of a panel with my improved contacter attached thereto, the cover of the contacter being shownin vertical section and the connectlons in diagram; Fig) 2 is a vertical section through the panel, contacter and casing, parts being shown in elevation. 4 9o The base 3 of the contacter is made of suitable insulating material and is designed to have the contacter proper and electromagnetic e rating means properly spaced thereon an separated by a wall 4 of insulating material which is preferably formed integral with the base. Saidwall is formed with an opening 5,v having a' purpose which will presently appear. The baseis formed with a rectangular boss or block 6, to which the stationary contact member 7 of the contacter is attached preferably by a screw bolt'8, extending through -the turned-ever ange 9 of said contact an the boss 6. The screw bolt the lead to the stationary contact. 'The movable contact com rises the arm 10, the outer end of which is nt orformed in a curve 11, which engages and rocks upon the at stationary! contact member. pair ne .in lugs on a bracket plate 16, so that it is not only free to revolve in said slots but also slides therein when the movable contact is operated to close or open the circuit. A'spring 17 is attached to the bracket 16 andas bent backwardly in a loop, its free end 18 extending beneath the pivot 13 and forcing the latter outwardly to the ends of the 4:lli

-is rapidly withdrawn to I substantial .arcing is avoided. It will be obslots.

The electro-magnetic operating device is as above stated separated from the contactor by the insulating wall 4. It is shown as comprising an electro-magnet 19, the armature 20 of which' is pivoted to a bracket 21 mounted onvthe same support 22 as the electro-magnet, an armor projection 23 being formed on the support for this purpose. The armature 2O is connected by a link 24 to a bracket 25 riveted to arm 10 of the movable contact. It will be seen that the constructionv is such that when the armature is attracted the movable contactor is first swung about the pivot 13 until the curved portion thereof engages the stationary contact and further pressure of the link :forces the pivot pin 13 along the slots against the pressure of spring 17 so 'that the curved end of the movable contact member rocks, and to some slight extent slides upon the fixed contact. The motion is such that any tendency to stick by reason of incipient fusion at the moment of closing the contacts is overcome and the friction between the contacts keeps them in good conductive condition. Obviously when the armature of the electro-magnetic device is released and retracted the movable contact such a distance that served that as the armature approaches the magnet the toggle composed of `armature 20 and link 24 straightens so that the power applied increases not onl by reason of the increased magnetioeld ut also because of the mechanical action of the toggle.

In Fig. 1 of the drawing I have shown diagrammatically the wiring of the device as applied to a cooling system in which a motor such as that of an ice machine is controlled. The leads 30, 31 extend to some source of alternating current which ordinarily wouldv be of about 110 volts. The lead 30il is attached to a post 32 which is connected by wire 33v at the back of the device to the bracket plate 16 which supports the movable element of the contactor and is in electrical connection therewith. The other binding post 33 of the .contactor is connected to the stationary contact thereof bywire 34, and to motorby wire 35. The circuit of the ymotor or heating device as `wire 43 to one of the terminals of the magnet coil. The other-terminal of the coil of the electro-magnet is connected to `o'r grounded. upon the base or support 61 of the electromagnet and the latter connected by wire44 to binding post 45. 1 Post 45 is' connected by4 wire 46 to the common neutral bi-metallic arm contact 47 ofthe thermostat. The other terminal of the secondary of the transformer 38 is connected by wire 48 /tol the 3s on contact 49 of the thermostat and also by wire 51 to binding post 52 of the electromagnetic device. Said Vbinding post is connected by wire 53 to a stationary contact 53. The latter is engaged by a movable on contact strip 54 attached to the armature when thek latter is in attracted position. The movable contact 54 is grounded or in electric contactwith the base 22 of the electrof magnet through the post 23.

Assuming as heretofore that the device is used to control the circuit of the motor of a refrigerating machine, when the temperature reaches the upper pre-determined'limit, the common element 47 of the thermostat makes 100 contact with the on stationary contact 49 whereupon a circuit is closed through the coil as follows: from the secondary of the transformer through wires 39, 41, post 42, wire 43, the coil of the electromagnet, support 22, wire 44, post 45, wire 46, switch 47, and wire 48 to the transformer. The magnet thus energized attracts its 'armatureclosing the contacter in the manner heretofore described and at the Sametime, swinging 110 contact 54 into engagement with contact 53".' Thus an additional path is closed from the terminal of the electro-magnet and support 22 through arm 23, contacts 54, 53, Wire 53, post 52, wires 51, 48. Therefore4 when the 115 temperature drops sufficiently to cause4 contact 47 to disengage contact 49, 'the electrof magnet will continue to hold the contactor in closed posit-ion. This condition 'will continue' until the temperature hasdropped Sufli- 120 ciently to cause the common contact 47 of the thermostat to engage off contact 50, whereupon the coil of the electro-magnet is sh0rtcircuited through the following path :,wire 39, :contacts 50, 47, wires 46, 44, base 61, contacts 54, 53', wire 53, post 52 and wires 51,48. The electro-magnet is thus de-energized releasing its armature. and the contactor is then opened.

By making the contacts 54, 53', or either 130 of them, of metal of a suitable degree of resilience, the opening movement of the armature is assisted in an obvious manner.

As heretofore stated, insulating intermediate Wall 4 prevents the hioh voltage our? rent being communicated to the electro-magnet-ic device, the. mechanical connection or link 24 being likewise of insulating material. Preferably the-device is provided with a cover 62 extending` over both the contactor and the electro-magnetic device which is held in place by a locking strip 63 secured on posts 64, 65, by suitable thumb nuts.

I claim A ,1. In a device ofthe class described, a stationary contact, a movable contact, one of said contacts being curved to rock upon the other, a pivoted arm carrying the movable contact, a pivot for said arm, a bracket having a slotted ear through which the pivot extends rand a spring connected to the bracket and bearing upon the pivot.

'2. In a device of the class described, a sta tionary contact, a movable contact, oneof said contacts beingcurved to rock upon the other, an arm carrying the movable contact,

a pivot on s'aid arm, a bracket having a slotted ear in which said pivot is movably mounted, a spring normally holding the pivot .in one end of said slot. and means for rotatingl said arm 4on its pivot and forcing the pivotto the other end of said slot agains the pressure of said spring.

3. Ina device of the class described, a stationary contact, a movable -contact, one

of said contacts being curved to r'ock upon' v the bracket through rock upon the stationary contact, a pivoted arm carrying the movable contact, a pivot on said arm, a plate having slotted lugs through which the pivot pin extends and a spring intermediate the plate and pivotpin.

' WILLIAM G. HARTWIG. 

